Oil base hydratable drilling fluid



Patented Nov. 23, 1937 I v i UNlTED STATES f n Q 1L BASE I I Ferdinand W. Rolshausen and Sam LIBishkin, Houston, Tex., assignors to. Standard Oil Development )ornpany, acorporation of' Delawai-e No Drawing. Application April '19,. 1935,

Serial No. 17,272

6 Claims. (of. 55 -1) In many oil-producing areas a formation comoxides, zinc dust, lead dust, or other metal fillers.

monly known as heaving shale" is frequently en- During the process ofgdrilling, water may be countered in the drilling of wells for oil or gas. picked up by. the drilling mud from the earth This formation is diflicult to penetrate. In rotary strata penetrated by the drill. Similarly, water drilling the bit which digs into the formations is may be formed by the reaction. during the prepturned by means of a pipe extending throughout aration of the drilling fluid. A readily hydratathe length of the hole being drilled. In order to ble material is addedto the drilling fluid to abremove the particles of sand, shale or rock cut sorb this water and prevent-the water from by the bit, mud is pumped into the pipe which contacting the heaving shale. The hydratable 10 rotates the bit. This mud ascends to the surmaterial may be a hydratable clay such as ben- 10 face of the ground exteriorly of the pipe and cartoniticclay, gelatin, agar agarfor the like. ries with it the rock particles cut by the bit. In order-to insure the substantially permanent In addition-to the removal of the cuttings, this suspension of the weighting material and the wamud fluid serves also for other useful purposes, ter absorptive material in the oil, a suitable l5 chief among which is to hold in the pores of the amount of soap producing materials is added to rock any water, oil or gas found in the formations the mixture. The base for such a soap producpenetrated. In order to do this, the hydrostatic ing mixture maybe lime, preferably added as ahead of the mud fluid must exceed the pressure suspension of hydrated lime inwater. Alternaon the fluids in the earth formations. tively, other substances by which soluble, partly Ordinarily the mud used in this work is a sussoluble or insoluble soaps can be produced may 20 pension of clay or other earth material in water. be used, for example, alkali metal oxides and hy- In drilling through heaving shale the hole is iredroxides, ammonium hydroxides, or the like. quently lost because the shale swells or disinte- These materials when combined with a suitable grates and fills the hole already drilled. Often acid radical will function as emulsifying agents this movement of the shale freezes or sticks the or suspending agents.

drill pipe and bit, making it diflicult or impossible An additional suspending or-dlspersing agent to remove the tools from the hole. An examinais preferably added to the mixture to render the tion of cores of this formation indicates that the suspension more stable and'more easy to handle. trouble is caused principally by hydration of the The additional agent may be crude oleic acid,

shale particles on contact with water. The water stearic acid, palmitic acid, or the like, which will 30 causes the shale'to swell or disintegrate and this react with the basic materials previously menswelling or disintegration is responsible for the tioned to form a soluble, partly soluble, or inmovement of the heaving shale into the hole soluble soap. of the drilling well. The water of the drilling It will be understood that either the basic mafluids previously-used hydrates the heaving shale terial or the acidic material may be omitted and 5 and causes the diflicult experiences in drilling some of the advantages of the invention will be this formation. retained. Both the acidic material and the basic It is an object of this invention to provide material function as suspending or dispersing a drilling fluid which will be inert to heaving agents. The hydrated lime is a suspension agent 40 shale and will not cause the shale to swell or disfor the solid material of the composition and it 40 integrate. serves also to emulsify water contamination, con- In accordance with the present invention, a verting it to the water-in-oil type of emulsion. non-aqueousdrilling fluid is provided, the base A suitable method of preparing the drilling or dispersion medium of whiith is non-aqueous fluid is as follows: l

material, inert to heaving shale. The non-aque- The oleic acid is added to a portion of the 45 ous material may be an oil. The oil may be a naphtha and stirred. The lime suspension is hydrocarbon such as a petroleum crude oil, disnext added and an insoluble soap is produced. tillate or residue. Tars of sufficiently low vis- To this soap naphtha mixture is added the .recosity may be used as the base fluid. The oil mainder of the naphtha and a required amount of may be a. crude oil which has been topped or gas crude barium sulfate to produce the desired den- 50 oil. Similarly, lubricating oils, kerosene, naphsity of drilling fluid. The materials are thortha and the like can be used. oughly stirred together, for example, by means of The oil base, such as naphtha, is preferably passing the me through acolloid machine or mixed with a. weighting material such as finely by pumping the materials to efiect thorough in-- divided barium sulfate, sand, calcined clay, iron termixinz. a

The resulting product weighs 11.7 lbs. per gal- We claim: Ion of fluid. It is sufllciently stable so that less, 1. A drilling fluid, comprising'an oil, a weightthan 01' 1% of the solid material separates from the body of the mixture over' a 24-hour period when the mixture undisturbed.

The resulting drilling fluid contact with tact with the heaving shale.

The foregoing description is merely illustrative of preferred forms of the invention and various changes may be made within the scope of the appended claims in which it is intended to claim all novelty as broadly as the prior art permits.

ing material, and a water-insoluble soap.

2. A drilling fluid for oil or gas wells, comprising an oil and an emulsifying agent adapted to form a water-in-oil emulsion.

3. A drilling fluid for oil or gas wells, comprising an oil, a weighting material and a water insoluble soap.

4. A drilling fluid for oil or gas wells, comprising an oil, a hydratable clay, and a water insoluble soap.

5. A drilling fluid comprising a petroleum oil and a reagent which forms a water in oilemulsion.

6. A drilling fluid comprising a petroleum oil, a. weighting material, hydrated lime, and a reagent which forms a water in oil emulsion.

FERDINAND W. ROIBHAUSEN. SAM L. BISImN. 

